A bridge is a data-link layer (Layer 2) internetworking device that interconnects two local area networks (LANs) such as Ethernet networks. Typically, the bridge may be transparent to end-node network devices because the end-node network devices may not be aware of the bridge. For example, the bridge may operate as a transparent bridge as described in the 802.1D standard developed by the Institute of Electrical and Electronic Engineers (IEEE) (e.g., the IEEE std. 802.1D, published 1999).
In particular, the transparent bridge may read the source and destination addresses in packets (or frames) and forward the packets on to another LAN segment depending on the addresses. A bridging table may be used to keep track of one or more bridge ports through which each destination may be reached (e.g., an outbound port). For example, if the bridging table includes a destination address of a packet and if the corresponding outbound port is any bridge port other than the inbound port through which the transparent bridge received the packet, the transparent bridge may forward the packet to the destination via the outbound port. Otherwise if the bridging table does not include the destination address of the packet, the transparent bridge may forward the packet via all bridge ports except for the inbound port of the packet.